Purpose:
The role of cerebrospinal fluid (CSF) dynamics in diseases of the optic nerve, like glaucoma, is coming under increasing scrutiny. In this study we examine the use of magnetic resonance imaging (MRI) as an approach to evaluate CSF movement and flow patterns within the perioptic subarachnoid space (POSAS) as a function of head and body position.

Results:
POSAS was consistently asymmetric in subject A and symmetric in subject B. The POSAS was consistently larger in the prone position compared to the supine position in both subjects. No significant difference was grossly noted in both lateral decubitus positions. CSF in the POSAS demonstrated movement in response to eye motion. In a static position, CSF movement was detected by Time-SLIP imaging, but was not pulsatile. Motion artifact and small target size reduced image quality.

Conclusions:
This pilot study suggests that CSF movement in ostensibly normal subjects occurs in response to gravity and is motion-dependent. This supports the notion that CSF within the optic nerve sheath moves, similar to other areas within the subarachnoid space. We also noted that the POSAS symmetry in ostensibly normal subjects varies. The results of this optimization study will be used to quantitate these findings and to begin looking at a larger number of subjects, both normal and those with diseases that affect the optic nerve like glaucoma.